At least 68 people have been killed by a series of simultaneous car bombs in Iraq's southern city of Basra in the deadliest terrorist attack there since the fall of Saddam Hussein. An agreement aimed at ending fighting with U.S. Marines in the western Iraqi town of Fallujah appears to have been short lived.

Anguish in Basra, Iraq's second largest city, where several car bombs, apparently the work of suicide bombers, exploded Wednesday morning near police stations. Among the dead were school children. British-patrolled Basra had been largely calm in the year since the fall of Saddam Hussein. In London, Britain's Foreign Secretary Jack Straw called the blasts the work of those who have no respect for the lives and future of the Iraqi people.

"These vicious attacks were deliberately targeted on those Iraqis who are working hard to build a new future," he said.

He said the attack will not disrupt plans for returning political power to Iraqis on June 30. At the White House, a spokesman called the blasts the work of thugs and terrorists.

The sound of heavy fighting returns to the western Iraqi town of Fallujah. Marines battled for several hours Wednesday with Sunni militants who they say have yet to turn in any of their heavy weapons as called for in an agreement aimed at preventing a threatened U.S. assault on the city. U.S. military officials have expressed skepticism that Fallujah's leaders could convince fighters in the town to turn in their weapons. Officials say the Marines are poised to move in with force to pacify the city if necessary.

With the level of American troops in Iraq expected to soon hit 135,000, Defense Secretary Donald Rumsfeld says the Pentagon does not rule out the possibility of sending even more troops there - beyond the 20,000 that have just had their tours of duty extended for 90 days.

"Are we considering it? No. Are we prepared? You bet," he said.

He made the comments as several members of the U.S.-led military coalition, including Spain and Honduras, announced they are pulling their troops out of Iraq. In light of that, Poland's Prime Minister says his government may have to reassess its military presence in Iraq as well. With more than 2,400 troops there, Poland is the fourth largest military contributor to the coalition and its forces command a 9,000-strong multi-national contingent on patrol in central Iraq. Following the outgoing prime minister's statement, a government spokesman said Poland is not considering a withdrawal of its troops.